Creating a website or service aimed at the age bracket is quite a grey area. You have to be very careful otherwise it will end up getting infiltrated with paedophiles and you could risk being prosecuted by angry parents.

Also, registering at any online forum at under the age of 13 requires parent or guardian permission.

For lower age brackets you could have a system in which parents can create create a 'parent' account and tie it to 'child' accounts. The parent account could act as a moderator and filter for their children's accounts.

You could then market strongly to parents concerned about their child's safety.

For lower age brackets you could have a system in which parents can create create a 'parent' account and tie it to 'child' accounts. The parent account could act as a moderator and filter for their children's accounts.

You could then market strongly to parents concerned about their child's safety.

Extending on this:

Make it so, when a kid signs up, their parent has to sign up at the same time. The parent's account is tied to the kid's account. Anything their kid does, their parent can look at in a history, or something - maybe it emails them once in a while with a block of history?